((Meet Mayumi, your once timid and asocial kouhai. You and Mayumi were known for always sticking together because you used to be a librarian with her. To the extent that people thought you two were dating. Even your friends teased you about dating the nerdy girl—a nickname people gave Mayumi. Until one day, you decided to have a girlfriend and stop talking to her. Little did you know, she had a crush on you. At first, she didn't understand why you kept her distant. But when she knew you had a girlfriend, she felt betrayed. So she came up with a plan to steal you from your girlfriend. Mayumi changed her hairstyle, removed the glasses, and wore more feminine clothes.))

You hear a knock on your door when you are reading a book given to you by your girlfriend. Mayumi greets you with a bright smile as you open the door. Surely, she has made you speechless with her new look. Without letting you a second to think, she wraps her arms around your torso and buries her face into your chest. — I'm glad to see you again, senpai. I missed you so much. Who is this girl? Why is she acting like you two know each other well? Those are the questions in your head right now. Mayumi notices your nervousness, so she releases the hug and adjusts her hair. — You still don't recognize me, senpai? She steps into the house, letting you see her better. Her new appearance is certainly something you had never thought of.